Isolator

ABSTRACT

An isolator is disclosed, in which a ferromagnetic sheet is placed into a shielding resin case together with garnet ferrite and an internal terminal sheet (with strip lines extending therefrom). Thus the leakage magnetic flux shielding effect is reinforced, and the bulk of the isolator is made compact. The constitution is as follows. That is, the internal terminal sheet (with the strip lines extending therefrom), a garnet ferrite, a plurality of insulating films and a ferromagnetic sheet are inserted into a shielding resin case in the cited order. Further, this structure is inserted into between upper and lower cases, and three dielectric devices and a chip resistor are disposed on a PCB and around the lower case, while a connecting terminal part with input/output terminals connected to the PCB electrodes is formed on the PCB.

FIELD OF THE INVENTION

[0001] The present invention relates to an isolator used in themicrowave apparatuses. More specifically, the present invention relatesto an isolator in which a ferromagnetic sheet (Sr-ferrite) together withan internal terminal sheet (with strip lines extending therefrom) and agarnet ferrite is inserted into a shielding case; dielectric devices anda chip resistor are installed on a PCB and around the shielding case; aconnecting terminal sheet is formed; and thus the ferromagnetic sheet issecurely placed by means of the strip lines of the internal terminalsheet and the garnet ferrite of the shielding case, so that the leakagemagnetic flux shielding effect can be reinforced, that the bulk of theisolator can be made compact, that the assemblability can be improved,and that the manufacturing process can be simplified.

BACKGROUND OF THE INVENTION

[0002] The generally known conventional isolator is inserted to betweenan antenna switch and a power amplifier module of a wireless apparatus,so that the signals reflected from the antenna switch are absorbed,thereby protecting the power amplifier module.

[0003]FIG. 1 is a block diagram of a system involving the isolator.

[0004] As shown in this drawing, transmission signals Tx are amplifiedby a power amplifier module 15, are filtered by a low pass filter 14,and are sent through an antenna switch 12 to an antenna 11, so that thesignals can be transmitted from the antenna 11.

[0005] Meanwhile, reception signals Rx are received by the antenna 11,and are sent through the antenna switch 12 to a band pas filter 16 so asto be filtered. Generally, an isolator 13 is disposed between theantenna switch 12 and the power amplifier module 15 of the wirelessapparatus, so that the signals reflected from the antenna switch 12 canbe absorbed, thereby protecting the power amplifier module 15.

[0006]FIG. 2 illustrates the basic equivalent circuit for the isolator.As shown in this drawing, an input terminal is coupled to an output partof the power amplifier module 15 of the transmitting part so as toreceive the transmission signals Tx. Further, the input terminal blockis connected an internal terminal block 22, and thus, the high frequencytransmission signals Tx are transferred to the internal terminal block22. An input capacitor C1 is connected between the input terminal blockand the ground.

[0007] Further, an output terminal block is connected to the internalterminal block 22, while the other end of the output terminal block isconnected to the antenna switch 12, so that the high frequency signalscan be finally transmitted from the antenna 11.

[0008] An output capacitor C2 is connected between the output terminalblock and the ground. A ground capacitor C3 and a longitudinal resistorR (50 Ω) are connected in parallel between the internal terminal block22 and the ground. The signals which have been transferred from thepower amplifier module 15 through the input terminal block and theinternal block to the output terminal block can reversely flow partlyfrom the antenna switch 12. These returned signals are sunk into theground from the internal block 22 through the longitudinal resistor R.

[0009] Therefore, the isolator 13 removes the power of the returningsignals so as to ultimately prevent the power amplifier module 15 frombeing damaged by the power of the returning signals, thereby protectingthe power amplifier module 15.

[0010]FIG. 3 is an exploded perspective view showing the constitution ofthe conventional isolator. As shown in this drawing, the isolatorincludes: an upper case 31; a ferromagnetic sheet (Sr-ferrite) 32 forgenerating a constant magnetic field owing to an input current; aninternal terminal block 33 disposed under the ferromagnetic sheet 32,for generating an induced magnetic field, and including a garnet ferrite42 and three strip lines 33′ connected to the input and output terminalblocks and to the ground; dielectric devices 35 a-35 c and a chipresistor 34 respectively connected to the three strip lines 33′ of theinternal terminal block 33; an injection-molded case 36 having throughholes 41 for fastening the internal terminal block 33, and having spacesfor receiving the chip resistor 34 and the three dielectric devices 35a-35 c, with input/output electrodes 38 and 39 and a ground electrode 37being accommodated therein; and a lower case 40.

[0011] In this conventional isolator, the arrangement of the componentsis as follows. That is, the ferromagnetic sheet 32 and the garnetferrite 42 are accommodated into the separate injection-molded case 36.Further, the three dielectric devices 35 a-35 c, the input/outputelectrodes 38 and 39, and the ground electrode 37 are horizontallyarranged, and they are connected through the strip lines of the internalterminal block 33. Accordingly, the sizes of the dielectric devices, thechip resistor and the garnet ferrite are increased, and therefore, theoverall bulk of the isolator is expanded.

[0012] Further, when the strip lines 331 of the internal terminal block33 are soldered to the dielectric devices 35 a-35 c and to theinput/output electrodes 38 and 39, soldering defects are apt to occurdue to the narrow space within the injection-molded case 36, as well asdegrading the workability and the assemblability of the isolator, andmaking it impossible to obtain uniform products.

SUMMARY OF THE INVENTION

[0013] The present invention is intended to overcome the above describeddisadvantages of the conventional technique.

[0014] Therefore it is an object of the present invention to provide anisolator in which a ferromagnetic sheet is securely placed by means ofstrip lines of an internal terminal sheet and a garnet ferrite, therebyimproving the shielding of the leakage magnetic flux to the degree ofmaximizing the shielding effect.

[0015] It is another object of the present invention to provide anisolator in which dielectric devices and a chip resistor are installedon a circuit board of the shielding case, thereby making the bulk of theisolator compact, making the response to the frequency easy, and makingthe characteristics of the product stable.

[0016] It is still another object of the present invention to provide anisolator in which the isolator can be easily installed on a circuitboard, thereby improving the assemblability, and simplifying themanufacturing process.

[0017] In achieving the above objects, the isolator according to thepresent invention includes: upper and lower cases; a ferromagnetic sheetdisposed within a shielding case, for generating a constant magneticfield owing to an input current; an internal terminal sheet having aplurality of strip lines for being connected to input/output electrodeterminals and a ground terminal and disposed under the ferromagneticsheet and a garnet ferrite, the garnet ferrite being for generating aninduced magnetic field; and the input/output electrode terminals and achip resistor and three dielectric devices for being connected to thethree strip lines of the internal terminal sheet, wherein theferromagnetic sheet is inserted into the shielding case together withthe garnet ferrite and the internal terminal sheet (with the strip linesextending therefrom), the shielding case is inserted into a lower metalcase, the three dielectric devices and the chip resistor are installedon a circuit board and around the lower metal case, and a connectingterminal part having the input/output electrode terminals is formed.

[0018] In another aspect of the present invention, the isolatoraccording to the present invention includes: upper and lower cases; aferromagnetic sheet disposed within a shielding case, for generating aconstant magnetic field owing to an input current; an internal terminalsheet having a plurality of strip lines for being connected toinput/output electrode terminals and a ground terminal and disposedunder the ferromagnetic sheet and a garnet ferrite, the garnet ferritebeing for generating an induced magnetic field; and the input/outputelectrode terminals and a chip resistor and three dielectric devices forbeing connected to the three strip lines of the internal terminal sheet,wherein the ferromagnetic sheet is inserted into the shielding resincase together with the garnet ferrite and the internal terminal sheet(with the strip lines extending therefrom) and a plurality of insulatingfilms, the shielding case is inserted into a lower metal case (servingas a ground), the three dielectric devices and the chip resistor areinstalled on a circuit board and around the lower metal case, and aconnecting terminal part having the input/output electrode terminals isformed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above objects and other advantages of the present inventionwill become more apparent by describing in detail the preferredembodiment of the present invention with reference to the attacheddrawings in which:

[0020]FIG. 1 is a block diagram of a system involving the isolator;

[0021]FIG. 2 illustrates the basic equivalent circuit for the isolator;

[0022]FIG. 3 is an exploded perspective view showing the constitution ofthe conventional isolator;

[0023]FIG. 4 is an exploded perspective view showing the constitution ofthe isolator according to the present invention;

[0024]FIG. 5 is a sectional view showing the structure of the isolatorbefore coupling the shielding case;

[0025]FIGS. 6a and 6 b are respectively a plan view and a bottom view ofa cavity PCB on which the isolator of the present invention isinstalled;

[0026]FIGS. 7a and 7 b are respectively a plan view and a bottom view ofa cavity PCB on which another embodiment of the isolator of the presentinvention is installed;

[0027]FIG. 8 is a frontal sectional view showing the assembled isolatorwhich is installed on the PCB of FIG. 7;

[0028]FIG. 9 is an exploded perspective view showing the constitution ofanother embodiment of the isolator according to the present invention;

[0029]FIG. 10 is a plan view of the PCB on which the isolator of FIG. 9is installed; and

[0030]FIG. 11 is a plan view showing a status in which the isolator ofFIG. 9 is installed on a PCB.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031]FIG. 4 is an exploded perspective view showing the constitution ofthe isolator according to the present invention.

[0032]FIG. 5 is a sectional view showing the structure of the isolatorbefore coupling the shielding case. FIG. 6 illustrates a cavity PCB onwhich the isolator of the present invention is installed. As shown inthese drawings, the isolator 100 according to the present inventionincludes: a ferromagnetic sheet 120 disposed between and within upperand lower cases 180 and 190, for generating a constant magnetic fieldowing to an input current; a garnet ferrite 140 disposed under theferromagnetic sheet 120, for generating an induced magnetic field, witha plurality of insulating films disposed above it; an internal terminalsheet disposed under the garnet ferrite 140; and a plurality of striplines 130′ extending up from the internal terminal sheet 130 to abovethe garnet ferrite 140.

[0033] Further, the strip lines 130′ of the internal terminal sheet 130are connected to a chip resistor 160, to three dielectric devices 150a-150 c, and to input/output electrode terminals 170 by soldering.

[0034] Under this condition, the ferromagnetic sheet 120 is insertedinto a shielding case 110, with the garnet ferrite 140 and the internalterminal sheet 130 (the strip lines 130′ extending therefrom) beinginvolved therein. A shielding is done by the upper and lower metal cases180 and 190. The chip resistor 160 and the three dielectric devices 150a-150 c are installed on a PCB 200 and around the lower case 190. Then aconnecting terminal part 210 with input/output terminals 170 insertedtherein is formed.

[0035] Now the present invention which is constituted as above will bedescribed as to its action and effects.

[0036] As shown in FIGS. 4 to 6, in the isolator according to thepresent invention, the ferromagnetic sheet 120 which generates aconstant magnetic field owing to an input current is disposed within theshielding case 110. In this state, under the ferromagnetic sheet 120,there is disposed the internal terminal sheet 130 from which the striplines 130′ extend to be contacted to the input/output terminals 170.

[0037] Under this condition, the strip lines 130′ of the internalterminal sheet 130 are connected to the three dielectric devices 150a-150 c and to the input/output electrode terminals 170 by soldering,thereby completing the isolator of the present invention.

[0038] Meanwhile, in the isolator 100, the ferromagnetic sheet 120 isinserted into a shielding case 110, with the garnet ferrite 140 and thestrip lines 130′ of the internal terminal sheet 130 being involvedtherein. Thus the variations of the magnetic field due to the damage orloose movements during its assembling can be inhibited, therebyreinforcing the leakage magnetic flux shielding effect.

[0039] Further, on the PCB 200 (which is made of a ceramic or alumina)and around the shielding case 110, there are installed the chip resistor160 and the three dielectric devices 150 a-150 c. Then a connectingterminal part 210 with the input/output terminals 170 formed therein isformed on the PCB 200. As a result, the assemblability of the terminalsis improved, while the chip resistor 160, the three dielectric devices150 a-150 c and the input/output terminals 170 can be easily connectedto the strip lines 130′ of the internal terminal sheet 130 by soldering.The strip lines 130′ extend from the inside of the shielding case 110 toits outside. Further, the shielding case 110 can be made to directlyserve as the ground terminal.

[0040] Meanwhile, FIGS. 7a and 7 b are respectively a plan view and abottom view of a PCB on which another embodiment of the isolator of thepresent invention is installed. As shown in these drawings, theferromagnetic sheet and the garnet ferrite of the isolator 100 areinserted into the center of the PCB 200′. In this state, on the PCB 200′and around the shielding case 110, the three dielectric devices 150a-150 c can be made to upstand.

[0041] Meanwhile, FIG. 9 is an exploded perspective view showing theconstitution of another embodiment of the isolator according to thepresent invention. As shown in this drawing, in the isolator 300, aferromagnetic sheet 320 which generates a constant magnetic field owingto an input current is installed within a shielding case 310 which ismade of a synthetic resin. Under the ferromagnetic sheet 320, there aredisposed a plurality of insulating films 420 which is made of polyimide.Under the plurality of the insulating films, there is disposed a garnetferrite 340 which generates an induced magnetic field. An internalterminal sheet 330 is disposed under the garnet ferrite 340. Further, aplurality of strip lines 330 extend from the internal terminal sheet 330to above the garnet ferrite.

[0042] Under this condition, the strip lines 330′ of the internalterminal sheet 330 are connected to the chip resistor 360, to the threedielectric devices 350 a-350 c and to the input/output terminals 370 bysoldering.

[0043] Meanwhile, the internal terminal sheet 330 (with the strip lines330′ extending up from it), the plurality of the insulating films 420,the garnet ferrite 340 and the ferromagnetic sheet 320 are inserted intothe shielding resin case 310 in the cited order. The shielding resincase 310 is inserted into the lower case which serves as a ground. Thenas shown in FIGS. 10 and 11, the three dielectric devices 350 a-350 cand the chip resistor 360 are installed on the PCB 400 and around thelower case 390. Then a connecting terminal part 410 with input/outputterminals 370 inserted therein is formed.

[0044] Thus in the isolator 300, the internal terminal sheet 330 (withthe strip lines 330′ extending up from it), the plurality of theinsulating films 420, the garnet ferrite 340 and the ferromagnetic sheet320 are inserted into the shielding resin case 310 in the cited order,which is made of a synthetic resin. Then this structure is accommodatedwithin and between upper and lower cases 380 and 390, and this assembledisolator 300 is installed on the PCB 400. Therefore, the variations ofthe magnetic field due to the damage or loose movements during itsassembling can be inhibited, thereby reinforcing the leakage magneticflux shielding effect.

[0045] Meanwhile, when the lower case 390 with the shielding case 310installed therein is installed on the PCB 400, that is, when theisolator 300 is installed on the PCB 400, a securing recess K can beformed on the PCB 400.

[0046] Further, the three strip lines 330′ of the internal terminalsheet 330 are drawn to the outside of the shielding case 310, so thatthe strip lines 330′ would be contacted to the three dielectric devices350 a-350 c and to the chip resistor 360. Under this condition, theshielding case 310 is provided with guide projections 430 for guidingthe strip lines 330′, and in this manner, any contact with the lowercase 390 is prevented.

[0047] Accordingly, the internal terminal sheet 330, the garnet ferrite340 and the ferromagnetic sheet 320 are inserted into the shielding case310 which is made of a synthetic resin. Therefore, the isolator of thepresent invention has an insulating characteristic. The strip lines 330′of the internal terminal sheet 330 are connected to the connectingterminal part 410 which is disposed on the PCB 400. Therefore, in theisolator of the present invention, the bulk can be made compact, and itsinstallation on the PCB 400 is convenient.

[0048] According to the present invention as described above, theferromagnetic sheet together with the garnet ferrite and the internalterminal sheet (with the strip lines extending from it) is inserted intothe shielding case of the isolator. Therefore, the leakage magnetic fluxshielding effect is reinforced, and the magnetic shielding effect can bemaximized. Further, the three dielectric devices and the chip resistorare installed on the PCB and around the lower case, and a connectingterminal part is formed adjacently. Therefore, the bulk of the isolatoris made compact, the frequency response is made easy, the productcharacteristics are made reliable, the installation of the product onthe PCB is made convenient, the assemblability of the product isimproved, and the production line is simplified.

[0049] In the above, the present invention was described based on thespecific embodiments and the attached drawings, but it should beapparent to those ordinarily skilled in the art that various changes andmodifications can be added without departing from the spirit and scopeof the present invention which will be defined in the appended claims.

What is claimed is:
 1. An isolator installed between a power amplifiermodule and an antenna switch, for transmitting output signals of saidpower amplifier module to said antenna switch, and for absorbingreflected signals from said antenna switch so as to protect said poweramplifier module, comprising: upper and lower cases 180 and 190; aferromagnetic sheet 120 disposed within a shielding case 110, forgenerating a constant magnetic field owing to an input current; aninternal terminal sheet 130 having a plurality of strip lines 130′ forbeing connected to input/output electrode terminals and a groundterminal, and disposed under said ferromagnetic sheet 120 and a garnetferrite 140, said garnet ferrite 140 being for generating an inducedmagnetic field; and said input/output electrode terminals and a chipresistor 160 and three dielectric devices 150 a-150 c for beingconnected to said three strip lines 130′ of said internal terminal sheet130, wherein said ferromagnetic sheet 120 is inserted into saidshielding case 110 together with said garnet ferrite 140 and saidinternal terminal sheet 130 (with said strip lines 130′ extendingtherefrom), said shielding case 110 is inserted into upper and lowermetal cases 180 and 190, said three dielectric devices 150 a-150 c andsaid chip resistor 160 are installed on a circuit board 200 and aroundsaid lower metal case 190, and a connecting terminal part 210 havingsaid input/output electrode terminals 170 is formed.
 2. The isolator asclaimed in claim 1 , wherein said three strip lines 130′ extending fromsaid internal terminal sheet 130 to an outside are connected to saidthree dielectric devices 150 a-150 c and to said input/output terminals170 of said PCB 200 by being soldered.
 3. The isolator as claimed inclaim 1 , wherein said three dielectric devices 150 a-150 c upstand onsaid PCB 200 and around said shielding case
 110. 4. The isolator asclaimed in claim 1 , wherein said shielding case 110 is made of aninsulating synthetic resin.
 5. An isolator comprising: upper and lowercases 380 and 390; a ferromagnetic sheet 320 disposed within a shieldingcase 310, for generating a constant magnetic field owing to an inputcurrent; an internal terminal sheet 330 having a plurality of striplines 330′ for being connected to input/output electrode terminals andto a ground terminal, and disposed under said ferromagnetic sheet 320and a garnet ferrite 340, said garnet ferrite 340 being for generatingan induced magnetic field; and said input/output electrode terminals anda chip resistor 360 and three dielectric devices 350 a-350 c for beingconnected to said three strip lines 330′ of said internal terminal sheet330, wherein said ferromagnetic sheet 320 is inserted into saidshielding resin case 310 together with said garnet ferrite 340 and saidinternal terminal sheet 330 (with said strip lines 330′ extendingtherefrom) and a plurality of insulating films 420, said shielding case310 is inserted into a lower metal case 390 (serving as a ground), saidthree dielectric devices 350 a-350 c and said chip resistor 360 areinstalled on a circuit board 400 and around said lower metal case 390,and a connecting terminal part 410 having said input/output electrodeterminals 370 is formed.
 6. The isolator as claimed in claim 5 , whereinsaid lower case 390 with said shielding case 310 inserted therein isinstalled on said PCB 400, and a securing recess K is formed on said PCB400 to secure said lower case
 390. 7. The isolator as claimed in claim 5, wherein said three strip lines 330′ extending from said internalterminal sheet 330 to an outside are connected to said three dielectricdevices 350 a-350 c and to said chip resistor 360 of said PCB 400 bybeing soldered.
 8. The isolator as claimed in anyone of claims 5 and 7,wherein said three strip lines 330′ extending from said internalterminal sheet 330 to an outside are connected to said three dielectricdevices 350 a-350 c and to said chip resistor 360 of said PCB 400 bybeing soldered.
 9. The isolator as claimed in claim 5 , wherein saidshielding case 310 is provided with guide projections 430 at angularintervals of 120 degrees, for guiding said strip lines 330′ (whichextend to the outside).
 10. The isolator as claimed in claim 5 , whereinsaid shielding case 310 is formed by an injection-molding process byusing an insulating synthetic resin.